The present invention relates to a sample holder to be used with an x-ray powder diffractometer. One of the novel aspects herein resides in the fact that the sample holder is made of single crystal silicon grown in the [100] direction. This sample holder may also have a cavity therein for holding the powder sample.
X-ray powder diffractometry is a commonly used analytical technique for determining qualitative and quantitative phase data about a substance. Fundamentally, the procedure involves directing a small beam of monochromatic x-rays onto a polycrystalline specimen and then recording the resultant pattern of diffracted x-rays as diffraction signal peaks on film or with a counter tube. Since different substances produce unique diffraction patterns because of their atomic arrangement, this technique serves as a `fingerprint` for identification of unknown materials.
The specimen to be analyzed in the above manner is placed on a sample holder which is then inserted into the diffractometer. The design of such a holder is important both for ease of use and for obtaining the best analytical results. For instance to obtain good results the holder should be made of a material which doesn't produce strong background signal intensity which may hide little peaks caused by the sample. Similarly, if the holder is made of a material which does produce large diffraction peaks, these peaks should be in an area of the diffraction pattern which doesn't interfere with interpretation of the diffraction peaks derived from the sample. For ease of use, the holder should be easy to clean, weigh and align, and it should be cost effective to manufacture.
Because of the above requirements, various sample holders have been designed and manufactured from aluminum, plastic and quartz. Each of these holders, however, has been found to have drawbacks. Aluminum holders, for instance, are relatively inexpensive to manufacture and they provide diffraction patterns with low background signal intensity. However, such holders do produce diffraction peaks in an area of the diffraction pattern which may interfere with interpretation of results. Similarly, plastic holders are inexpensive to manufacture and their diffraction pattern doesn't contain sharp diffraction peaks which interfere with analysis of the results. These holders do, however, produce diffraction patterns with relatively high background signal intensity and they are often difficult to clean. Finally, quartz holders are advantageous in that they produce a good diffraction pattern with low background signal intensity and few diffraction peaks which interfere with analysis of the results. Quartz holders, however, are fragile and very expensive to manufacture into the desired shape and form.
The present inventors have now discovered a sample holder which avoids the above problems associated with the prior art.